Process of making box toe stock



Unite States Patent PROCESS OF MAKING BOX TOE STOCK Eric W. Lennon, Lennoxville, Quebec, Canada, assignor to Beckwith-Arden Inc., Water-town, Mass., a corporation of New Hampshire No Drawing. Filed Feb. 6, 1957, Ser. No. 638,440

6 Claims. (Cl. 154-102) This invention comprises a new and improved process of making sheet stock from which box toes of superior quality of thermoplastic and solvent-softenable types may be formed with important savings in cost.

One commercial type of box toe stock heretofore available to the shoemaking industry consists of a woven cotton base impregnated and coated with butadienestyrene stiffening compound of the solvent-softening type in an amount approximately 60-78% of the weight of the stock. In forming box toe blanks from such sheet stock there is an unavoidable waste in cutting and skiving of the blanks that amounts to as much as 25%. This waste scrap has heretofore been burned as the least troublesome Way of disposing of it.

I have now discovered that the scrap formerly wasted may be utilized with great economy and transformed into box toe stock superior to the original in several respects. It possesses a more permanent and higher degree of resiliency and more of the desirable characteristic known as snap than is found in the original stock. It may be utilized as either a solvent type box toe or pulled in the dry or heated state similar to the techniques applied to the common snap-back box toes available to the shoemaking industry. Its high resistance to water and changes in humidity is an improvement over the present sandwich-type of box toe now available.

The process of my invention is carried out by first shredding the scrap material, then mixing with an organic solvent, adding a somewhat critical amount of nonsolvent, further mixing and finally calendering as sheet stock.

Going more into detail, the cutting and skivin-g waste is first subjected to shredding in a hammer mill in which rotary hammers shred the waste against a series of stationary bars as a dry operation. The shredded stock 'will be found to comprise. 30% cotton and 70% butadiene-styrene compound or thereabouts. I

The shredded stock is now subjected to the action of a jacketed mixer with the addition of about 40 parts of a suitable organic solvent to 60 parts by weight of the shredded material, the organic solvent being .added in small increments as the mixing operation progresses. The material is thus reduced to a sticky mass containing very small lumps not reached by the solvent. It does not pull down on the blades but tends to stick more or less to the walls and bottom of the mixer. Any suitable organic solvent or solvent mixture may be used for the mixing step such as the aliphatic and aroamtic solvents. As an example, parts by volume of the cominercially available Solvesso 150 maybe advantageously mixed with 90 parts by volume of toluol. In general it is desirable to use a solvent or mixture having a high flash point together with a moderate rate of evaporation. .Solvesso 150 alone tends to evaporate too slowly but when cut with toluol is entirely satisfactory.

After 10 or minutes of mixing with solvent, 9 /2 to 10 parts of an organic non-solvent is added to the mass 2,959,510 Patented Nov. 8, 1960- ICC in the mixer whereupon the character of the mass will be found to change rapidly in that it immediately pulls smoothly down on the blades of the mixer and becomes stretchy and tough. After the addition of the non-solvent, mixing should be continued for 10 to 20 minutes. Satisfactory non-solvents are found to be methyl,'ethyl or isopropyl alcohols. Although the addition of this critical volume of non-solvent results in little or no adhesion to the metal of the enclosing mixer, the mass still retains a high adhesion to textile fabric and this property makes possible the spreading upon or sandwiching between such fabrics.

At the conclusion of the mixing operation the mass may be removed and placed in a sealed container in order to allow the solvent to migrate and to permeate the entire mass and any lumps contained therein. The mass may be allowed to remain almost indefinitely in the sealed container but preferably for at least a few hours. The container also serves as a reservoir in which the material may be held for final mixing and calendering and from which it may be drawn from time to time in convenient routine.

At the conclusion of this step the desired amount of now thoroughly permeated material is withdrawn from the reservoir and the put back in the mixer for a final mixing of 10 or 15 minutes in preparation for calendering. This final mixing may be carried out with the material either in a cold condition or very slightly warmed if it has remained in sealed condition for an extended period.

The calendering operation may be carried out in accordance with the character of the stock desired. It

may be calendered on one side of cotton fabric, or'between two sheets of cotton fabric either napped or unna-pped, or any combination thereof, or without the addition of a textile sheet.

In a final operation the calendered stock may be dried by running it over steam heated rolls which may be sup plemented by infra-red drying lamps.

When preparing continuous sheet stock without the addition of any textile fabric it is calendered as a thin semi-opaque film and dried in the manner mentioned. This film may be cut into box toe blanks which when solvent activated and inserted between the inner and outer integuments of the shoe will bind them together thus forming a stiff yet highly resilient dome or shell. This particular application of the sheeted scrap material presents an innovation in box toe technique in that the upper leather and lining, or doubler and lining, are in themselves welded together by means of a thin plastic and adhesive film, which upon loss of its solvent through evaporation leaves a firmly bonded multi-ply dome of high resilience.

Box toe blanks cut from the sheet stock are highly resistant to moisture. They may be activated either by heat, or by suitable organic solvent. They may also be pulled or lasted with the other component of a shoe upper in the dry and cold condition it so desired. 'Sheet stock comprising two plies of fabric (sandwich style) may be cut into toe blanks and lasted either with heat activation or in the cold condition using latex cement as a bonding agent. Its use is applicable to either lined or unlined shoes. If the same double plymaterial is intended for box toe blanks of the solvent softening type it is desirable to spray and dry one or both surfaces of the stock with the same butadiene-styrene compound of the original material, in order to supply the box toe with the proper adhesive properties. Such stock as is sprayed on both surfaces will be suitable for lined footwear, while the stock sprayed on one surface will serve for unlined shoe.

When the sheet stock comprises a single ply of fabric it may be cut into box toe blanks affording an exposed surface of butadiene-styrene which when activated with solvent becomes soft and adhesive and may be used in unlined shoes forming a firm bond with the outer integuments of the upper while leaving the wood of the last clean and free of adhesions. If during the manufacturing procedure this latter material be sprayed with the butadiene-styrene compound on its fabric side it offers two adhesive surfaces, thus when activated with solvent may be used in lined shoes.

Instead of using waste stock as above described the cotton may be supplied to the mixer in the form of cotton flock and powdered butadiene-styrene compound added to it with the solvent in the mixer. The mass produced contains the same relative amount of cotton and stiffening compound as derived from the waste-material but in addition varying amounts of other ingredients may be added if so desired such as talc, asbestos fibre, wood flour or other common fillers, and of course any selected dye may be added to the scrap mixture or to the cotton flock mixture.

An unexpected advantage of the box toe stock of my invention is that the box toe blanks dry out in the shoe quicker than blanks made from the original stock. Apparently the presence of the shredded cotton fibres in intimate and dense admixture with the butadiene-styrene act as an absorbent and carrier for the solvent and accordingly increase the rate of solvent migration to the external surfaces ofthe box toe and into contact with the atmosphere thus facilitating evaporation thereof.

Ordinarily the shredding operation will be carried to the point of reducing the waste scrap to a condition substantially free of discrete yarns or fibres but increased tensile strength may be secured in the product if the shredding step is terminated so that the mass arriving at the mixer will contain some residual strands of yarn or fibre.

While a butadiene-styrene compound of a specific composition has been referred to herein, any stiffening compound of the same characteristics may be employed without departing from the invention.

Having thus disclosed my invention and described in detail an illustrative process of carrying it out, I claim as new and desire to secure by Letters Patent:

1. The process of making box toe stock which is both thermoplastic and solvent-softenable, characterized by the steps of shredding dry scrap sheet material consisting approximately of 30% by weight cotton fabric and 70% by weight solid butadiene-styrene compound, mixing 60 parts by weight of the shredded material with approximately 20 parts by weight of organic solvent added progressively thus forming a sticky mass, adding as a critical amount 9 /2 to parts by weight of a non-solvent alcohol thus imparting to the sticky mass a tough, stretchy consistency, subjecting the mixture to a period of solvent permeation, then further mixing the solvent-permeated mixture in a cool state and calendering upon a textile fabric the cool mixed mass including therein the shredded cotton component prepared as above set forth, thereby producing sheet box toe stock having the property of quick drying and hardening after it has been solvent-softened preparatory to incorporation in a shoe upper.

' 2. The process of making box toe sheet stock which is both thermoplastic and solvent-softenable, characterized by the steps of dry shredding scrap sheet material consisting approximately of 30% cotton and 70% by weight butadiene-styrene compound, mixing 60 parts, by weight, of the shredded sheet material with approximately 20 parts, by weight, of organic solvent added progressively and thus forming a sticky mass, adding to the sticky mass thus formed 10 parts of a non-solvent alcohol, subjecting the sticky mass to solvent permeation for a substantial period of time thus converting the sticky mass to a tough, stretchy consistency, subjecting the solvent-pen meated mass to cool mixing, calendering upon a textile sheet the cool mixed mass including therein the Shredded cotton component prepared as above set forth, and drying the resulting calendered sheet stock to a'stifi resilient consistency.

3. The process of making box toe sheet stock which is both thermoplastic and solvent-softenable, characterized by the steps of shredding dry sheet material consisting of cotton and butadiene-styrene compound, mixing the shredded sheet material with an organic solvent and thus forming a sticky mixture, adding to the sticky mixture a non-solvent of butadiene-styrene selected from the group consisting of methyl, ethyl and isopropyl alcohols, thus imparting to the sticky mixture a tough, stretchy consistency, subjecting this mixture to permeation by the organic solvent, further mixing the now solvent permeated mass, calendering between two textile sheets in sandwich fashion the mixed mass including therein the shredded cotton component prepared as above set forth and drying the calendered sheet stock thus formed.

4. The process of making box toe stock which is both thermoplastic and solvent-softenable, characterized by combining cotton flock and dry powdered butadienestyrenecompound in proportion approximately 30 to by weight of the two components, mixing these components with an organic solvent and thus forming a sticky mixture, adding to the sticky mixture a non-solvent of butadiene-styrene selected from the group consisting of methyl, ethyl and isopropyl alcohols thereby imparting to the sticky mixture a tough, stretchy consistency, subjecting the mixture to permeation by the organic solvent for a substantial period of time, further mixing the now solvent-permeated mass, calendering upon a textile fabric the solvent-permeated mass, and drying the calendered sheet stock thus formed to flexible resilient consistency.

5. The process of claim 4 characterized by the additional step of spraying the surface of the textile fabric with butadiene-styrene latex just prior to the final drying step thereby assuring a surface which will become adhesive when solvent activated.

6. The process of making box toe sheet stock which is both thermoplastic and solvent-softenable, characterized by the steps of shredding dry box toe waste consistingof cotton and butadiene-styrene compound in sheet form, mixing the shredded sheet material with an organic solvent thus forming a sticky mixture, adding to the mixture a non-solvent of butadiene-styrene selected from the group consisting of methyl, ethyl and isopropyl alcohols thereby imparting to the sticky mixture a tough, stretchy consistency, subjecting the mixture to permeation by the organic solvent for a substantial period of time, further mixing the now solvent-permeated mixture, calendering the mixture including therein the shredded cotton proponent prepared as above set forth and thereby transfornlling it to a continuous, flexible film of resilient sheet stoc References Cited in the file of this patent UNITED STATES PATENTS 2,033,727 Miller et al Mar. 10, 1936 2,600,461 Backus June 17, 1952 2,611,719 Borders Sept. 23, 1952 2,638,457 Gates May 12, 1953 2,698,816 Dosmann et al Jan. 4, 1955 

1. THE PROCESS OF MAKING BOX TOE STOCK WHICH IS BOTH THERMOPLASTIC AND SOLVENT-SOFTENABLE, CHARACTERIZED BY THE STEPS OF SHREDDING DRY SCRAP SHEET MATERIAL CONSISTING APPROXIMATELY OF 30% BY WEIGHT COTTON FABRIC AND 70% BY WEIGHT SOLID BUTADIENE-STRYENE COMOUND, MIXING 60 PARTS BY WEIGHT OF THE SHREED MATERIAL WITH APPROXIMATELY 20 PARTS BY WEIGHT OF ORGANIC SOLVENT ADDED PROGRESSIVELY THUS FORMNG A STICKY MASSS, ADDING AS A CRITICAL AMOUNT 91/2 TO 10 PARTS BY WEIGHT OF A NON-SOLVENT ALCOHOL THUS IMPARTING TO THE STICKY MASS A TOUGH, STRETCHY CONSISTENCY, SUBJECTING THE MIXTURE TO A PERIOD OF SOLVENT PERMEATION, THEN FURTHER MIXING THE SOLVENT-PREMEATED MIXTURE IN A COOL STATE AND CALENDERING UPON A TEXTILE FABRIC THE COOL MIXED MASS INCLUDING THEREIN THE SHREDDED COTTON COMPONENT PREPARED AS ABOVE SET FORTH, THEREBY PRODUCING SHEET BOX TOE STOCK HAVING THE PROPERTY OF QUICK DRYING AND HARDENING AFTER IT HAS BEEN SOLVENT-SOFTENED PREPARATORY TO INCORPORATION IN A SHOE UPPER. 